Our prior application, Ser. No. 09/303,839, describes a novel electrosurgical handpiece for treating tissue in a surgical procedure commonly known as minimally invasive surgery (MIS). Among the features described and claimed in the prior application is an electrosurgical handpiece that can be used in MIS and allows a surgeon or other practitioner to replace in the handle a bipolar electrode with a unipolar electrode, or vice-versa, in the midst of a surgical procedure. For example, the surgeon may desire to use a particular unipolar electrode for a cutting procedure and follow it up using a bipolar electrode to coagulate any bleeders. This is achieved in one embodiment by a handle construction to accommodate other electrode ends, by sliding out an inner tubular member from an outer tubular member and sliding in its place another inner tubular member with a different electrode configuration. This can be done before the outer tubular member is extended through a cannula into the patient or even while the cannula is in place within the patient. In addition, a bipolar assembly in its dual lumen arrangement can be replaced by a unipolar electrode in a lumen with only a single compartment, in which case, the unipolar electrode end, with one of the several electrode shapes, would project forward from the end of the inner tubular member. When an electrode substitution is to be made, the surgeon can pull out the inner tubular member and replace it with another inner tubular member with a different electrode thereby enabling the surgeon to change electrodes during the procedure without removing the handle with its outer tubular member that has already been strategically placed in the surgical site. That concept of interchangeable unipolar and bipolar electrodes has been extended in the present application to cover the use of many conventional as well as novel electrode constructions.